Aug 18, 2016 - AQP7 (r = 0.80), ACAA2 and FABP3 (r = 0.78) and ELF1 and PPAP2A (r = 0.75). Interestingly, the strong corre- lation between PPARG and ...
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OPEN
received: 12 February 2016 accepted: 26 July 2016 Published: 18 August 2016
Expression-based GWAS identifies variants, gene interactions and key regulators affecting intramuscular fatty acid content and composition in porcine meat Anna Puig-Oliveras1,2, Manuel Revilla1,2, Anna Castelló1,2, Ana I. Fernández3, Josep M. Folch1,2 & Maria Ballester1,2,4 The aim of this work is to better understand the genetic mechanisms determining two complex traits affecting porcine meat quality: intramuscular fat (IMF) content and its fatty acid (FA) composition. With this purpose, expression Genome-Wide Association Study (eGWAS) of 45 lipid-related genes associated with meat quality traits in swine muscle (Longissimus dorsi) of 114 Iberian × Landrace backcross animals was performed. The eGWAS identified 241 SNPs associated with 11 genes: ACSM5, CROT, FABP3, FOS, HIF1AN, IGF2, MGLL, NCOA1, PIK3R1, PLA2G12A and PPARA. Three expression Quantitative Trait Loci (eQTLs) for IGF2, ACSM5 and MGLL were identified, showing cis-acting effects, whereas 16 eQTLs had trans regulatory effects. A polymorphism in the ACSM5 promoter region associated with its expression was identified. In addition, strong candidate genes regulating ACSM5, FOS, PPARA, PIK3R1, PLA2G12A and HIF1AN gene expression were also seen. Notably, the analysis highlighted the NR3C1 transcription factor as a strong candidate gene involved in the regulation of the 45 genes analysed. Finally, the IGF2, MGLL, MC2R, ARHGAP6, and NR3C1 genes were identified as potential regulators co-localizing within QTLs for fatness and growth traits in the IBMAP population. The results obtained increase our knowledge in the functional regulatory mechanisms involved in these complex traits. Pork-meat cuts and their derived products are paid according to the lean percentage in pork carcasses and meat quality, since they determine better acceptance for consumers1. A high amount of backfat content is a less desirable trait; meanwhile, meat with high intramuscular fat (IMF) is considered to have better taste, conferring juiciness to the meat. Additionally, fatty acid (FA) composition of IMF affects meat nutritional and sensory quality parameters. Monounsaturated FAs (MUFA) confer more oxidative stability than do polyunsaturated FAs (PUFA), improving meat taste and colour2. Furthermore, PUFA decreases the risk of suffering cardiovascular diseases, being healthier than saturated FAs (SFA)3. Therefore, there is a consumer requirement for porcine meat with high IMF with a balanced FA composition. Some pig breeds, such as Landrace, have undergone an intense selection process towards efficient meat production with rapid growth and a leaner carcass; however, its resulting meat is less appreciated by consumers due to having low IMF composed of a high proportion of PUFA content4. In contrast, rustic pigs, such as the Iberian, are fatter, with more IMF with higher SFA and MUFA content and lower PUFA concentrations, which yields high quality and tasty meat, especially for dry-cured products. For instance, when comparing Iberian pigs with commercial breeds, Iberian pigs show higher palmitoleic acid (C16:1(n-7); 4.08 vs. 3.31; p
